A semiconductor element has to satisfy a large number of requirements, and has to have a certain minimum life. However, semiconductor elements are generally highly sensitive, so that environmental influences can adversely affect the operation of an element such as this, and can considerably shorten its life. Once a semiconductor element has been produced, it is therefore generally fitted with a housing in order to protect the semiconductor element against environmental influences. The housing which is generally used in semiconductor technology is generally in form of a molding compound composed of organic polymers (typically thermosetting plastics based on epoxy resins such as Orthocresolnovolac), which are applied to the semiconductor element by extrusion coating. A semiconductor element which has been packed in this way is subjected after its production to further process steps, with the various process steps being carried out at different temperatures, so that a semiconductor element such as this is repeatedly subjected to temperature loads. In order to make it possible to effectively protect the semiconductor element against the environmental influences, a housing must be in close contact with the semiconductor element in widely different conditions, and it must not have any tendency to separation. It is thus necessary for the adhesion of the molding compound to all of the exposed surfaces of the semiconductor element (or the chip) to be set such that no separation (delamination) occurs in repeatedly changing temperature conditions. A semiconductor element is generally composed of metallic and non-metallic parts, which have different adhesion characteristics with respect to the molding compound. Both the metallic surfaces and the non-metallic surfaces must therefore be prepared in separate steps, so as to ensure the adhesion to the molding compound.
In order to improve the adhesion between the metallic surfaces and the housing, a further, suitably, roughened metallic layer is deposited on all of the metallic surfaces which are in contact with the molding compound, before the production of the housing. Electrochemical deposition is particularly suitable for deposition of this metallic layer, in order to make it possible to deposit filaments in the nanometer range, which considerably improves the adhesion between the metallic surface and the molding compound.
A layer composed of a polyimide polymer is applied to the non-metallic surfaces in order to improve the adhesion of the non-metallic surfaces of a semiconductor element to the molding compound. However, since the adhesion between the metallic surface and the polyimide polymer is not optimal, a further layer, which is referred to in the following text as a passivation layer, must be applied underneath the polyimide polymer. This passivation layer, which improves the adhesion between the polyimide and the metallic surfaces, is preferably composed of a dielectric, such as silicon nitride or silicon oxide.
The object of the present invention is to provide a semiconductor element which can be provided with a housing without having to apply a passivation layer to the non-metallic surfaces.